import java.util.HashMap;
import java.util.Scanner;

/**
 * 字符个数统计
 */
public class HJ10 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String numStr = sc.nextLine();
            char[] numStrCharArray = numStr.toCharArray();
            int sum = 0;
            HashMap<Object, Object> charMap = new HashMap<>(16);
            for (char c : numStrCharArray) {
                Object o = charMap.get(c);
                if (o == null) {
                    charMap.put(c, c);
                    sum++;
                }
            }
            System.out.println(sum);
        }
    }
}
